system/{greetd,gui}: slight refactor

modules/system/greetd.nix

@@ -8,4 +8,9 @@
       };
     };
   };
+
+  services.xserver = {
+    autorun = false;
+    displayManager.startx.enable = true;
+  };
 }

modules/system/gui.nix

@@ -24,11 +24,7 @@
   };
   services.xserver = {
     enable = true;
-    autorun = false;
+    displayManager.lightdm.enable = lib.mkForce false;
-    displayManager = {
-      lightdm.enable = lib.mkForce false;
-      startx.enable = true;
-    };
     desktopManager.xterm.enable = false;
   };
 }